Oxygen breathing system with programmed oxygen delivery

Abstract

The oxygen breathing system with programmed oxygen delivery comprises a breathing circuit which a user exhales into and inhales from and a source of oxygen which delivers oxygen to the breathing circuit at a programmed rate. The oxygen is supplied at a high rate during the initial period of operation and at a low rate during the remaining period of operation. An overpressure relief valve in the breathing circuit opens during the initial time period because of the high oxygen delivery rate thereby flushing from the breathing circuit the nitrogen initially residing in the lungs of the user and in the breathing circuit. As a result of the flushing, the oxygen content in the breathing circuit approaches 100 percent at the end of the initial period and remains near this level during the subsequent time period. The source of oxygen can be a chemical reaction which occurs when a chemical compound is combined with a liquid in which case the programmed oxygen delivery is achieved by metering the liquid that is added to the chemical compound. Alternatively, the source of oxygen can be a storage container of oxygen or a contained chemical reaction and the programmed oxygen delivery is accomplished with a valve having a programmed flow rate.

What is claimed is: 
     
       1. An oxygen breathing system comprising: a means by which a user exhales gases into and inhales gases out of the system;   a breathing circuit for receiving the exhaled gases from the user and delivering a mixture of some of the exhaled gases and oxygen to the user when the user inhales, the breathing circuit having an inlet for receiving the oxygen; and   a means for supplying oxygen through the inlet to the breathing circuit at a delivery rate that varies with time from an initial rate to a final rate.   
     
     
       2. The oxygen breathing system of claim 1 wherein the oxygen supplying means is an oxygen generator, the generation resulting from a chemical reaction. 
     
     
       3. The oxygen breathing system of claim 2 wherein the chemical reaction is between a chemical compound and a liquid, the oxygen generator comprising: a liquid container having an outlet through which the liquid can flow;   a reactor wherein the chemical reaction takes place, the reactor having a space for receiving the chemical compound, the reactor having an inlet through which the liquid can flow into the space occupied by the chemical compound, the reactor inlet being connected to the liquid container outlet, the reactor having an outlet for the gases generated as a result of the chemical reaction to exit the reactor, the outlet of the reactor being connected to the inlet of the breathing circuit; and   a means for controlling the flow of liquid from the liquid container to the reactor in accordance with a predetermined function of time.   
     
     
       4. The oxygen breathing system of claim 3 wherein the chemical compound is sodium perborate anhydrous (NaBO 3 ) and the liquid is water. 
     
     
       5. The oxygen breathing system of claim 3 wherein the flow of liquid from the liquid container to the reactor occurs as a result of gravity, the liquid flow controlling means comprising: a pipe fastened at one end to a float and closed at the other end, the float causing the pipe to be vertically suspended in the liquid with the proximal end of the pipe near the surface of the liquid, the pipe having holes through the pipe wall at at least two levels, a level being a predetermined distance from the distal end of the pipe, there being at least one hole on the circumference of the pipe at each of the levels, the cross-sectional shape of the pipe transverse to the pipe axis being the same as the outlet of the liquid container, the pipe and the outlet being so arranged that the pipe can slide freely through the outlet as the level of the liquid in the liquid container decreases.   
     
     
       6. The oxygen breathing system of claim 3 wherein the reactor comprises: a gas absorption device which absorbs at least a portion of at least one undesired gas that is produced as a result of the chemical reaction, the gases produced as a result of the chemical reaction having to flow through the gas absorption device to reach the reactor outlet.   
     
     
       7. The oxygen breathing system of claim 6 wherein the gas absorption device comprises; an odor absorber; and   a water vapor absorber.   
     
     
       8. The oxygen breathing system of claim 3 wherein the reactor comprises: a flow rate limit valve which limits the flow rate of gases exiting the reactor via the reactor outlet; and   an overpressure relief valve which provides an exit for gases in the reactor when the gas pressure in the reactor exceeds a predetermined level.   
     
     
       9. The oxygen breathing system of claim 8 wherein the reactor further comprises: a check valve which prevents gases from entering the reactor through the reactor outlet.   
     
     
       10. A method of using the system of claim 3 comprising the steps: placing sodium perborate anhydrous (NaBO 3 ) in the reactor;   placing water in the liquid container; and   exhaling into and inhaling from the breathing circuit.   
     
     
       11. The oxygen breathing system of claim 1 wherein the breathing circuit comprises: an overpressure relief valve which provides an exit for gases in the breathing circuit when the oxygen delivery rate into the breathing circuit exceeds a predetermined level.   
     
     
       12. The oxygen breathing system of claim 11 wherein the predetermined oxygen delivery rate exceeds the predetermined level during an initial time period and does not exceed the predetermined level during a subsequent time period thereby causing the oxygen content of the breathing circuit to approach 100 percent by the end of the initial time period and to remain near this level during the subsequent time period. 
     
     
       13. The oxygen breathing system of claim 1 wherein the oxygen supplying means is an oxygen storage and delivery apparatus. 
     
     
       14. The oxygen breathing system of claim 13 wherein the oxygen storage and delivery apparatus comprises: an oxygen cylinder for storing oxygen; and   a programmed flow rate valve attached to the oxygen cylinder, the flow rate valve having an outlet that connects to the inlet of the breathing circuit, the programming of the flow rate valve being such that the oxygen delivery rate is the predetermined function of time.   
     
     
       15. The oxygen breathing system of claim 14 wherein the programmed flow rate valve comprises: a controllable flow rate valve; and   a controller that causes the oxygen delivery rate through the controllable flow rate valve to be in accordance with the predetermined function of time.   
     
     
       16. An oxygen breathing system comprising: a means by which a user exhales gases into and inhales gases out of the system;   a breathing circuit for receiving the exhaled gases from the user and delivering a mixture of some of the exhaled gases and oxygen to the user when the user inhales, the breathing circuit having an inlet for receiving the oxygen; and   a means for supplying oxygen through the inlet to the breathing circuit, the oxygen being obtained by combining sodium perborate anhydrous (NaBO 3 ) and water.   
     
     
       17. The oxygen breathing system of claim 16 wherein the sodium perborate anhydrous is combined with a surfactant, thereby generating oxygen without foaming. 
     
     
       18. A method for supplying a person with oxygen for breathing, the oxygen being obtained by means of a chemical reaction, the method comprising the steps: receiving the gases exhaled by the person;   providing a flow of oxygen at a rate that varies with time from an initial oxygen-flow rate to a final oxygen-flow rate   by adding a liquid to a chemical compound at a rate that varies with time from an initial liquid-flow rate to a final liquid-flow rate, the chemical reaction between the liquid and the chemical compound resulting in the generation of oxygen at a rate that varies with time from the initial oxygen-flow rate to the final oxygen-flow rate;   mixing the exhaled gases and the oxygen; and   supplying the mixture of exhaled gases and oxygen to the person for inhalation.   
     
     
       19. A method for supplying a person with oxygen for breathing, the oxygen being obtained by means of a chemical reaction, the method comprising the steps: receiving the gases exhaled by the person;   providing a flow of oxygen at a rate that varies with time from an initial oxygen-flow rate to a final oxygen-flow rate;   mixing the exhaled gases and the oxygen;   supplying the mixture of exhaled gases and oxygen to the person for inhalation;   removing at least a portion of at least one undesired gas, at least a portion of the odorous gases and at least a portion of the water vapor that accompany the oxygen.   
     
     
       20. A method for supplying a person with oxygen for breathing comprising the steps: receiving the gases exhaled by the person;   providing a flow of oxygen at a rate that varies with time from an initial oxygen-flow rate to a final oxygen-flow rate;   mixing the exhaled gases and the oxygen; and   supplying the mixture of exhaled gases and oxygen to the person for inhalation;   wherein oxygen is provided at a rate that exceeds a predetermined level during an initial time period and does not exceed the predetermined level during a subsequent time period, the method further comprising the step: discarding a portion of the mixture of exhaled gases and oxygen during the time period when the oxygen is generated at a rate that exceeds the predetermined level thereby causing the oxygen content of the gas mixture supplied to the person for inhalation to approach 100 percent by the end of the initial time period and to remain near this level during the subsequent time period.